This invention relates to a semiconductor apparatus, in particular, to a semiconductor apparatus comprising a driving device and a driven device which are connected with a transmission line.
A related semiconductor apparatus comprises a driver (or a driving device), a receiver (or a driven device) and a transmission line (or a bus) connected between the driver and the receiver. The driver has output impedance Zout while the transmission line has impedance Z0.
If the driver, the receiver and the transmission line are ideal, an output signal of the driver travels to the receiver on the transmission line without being damped. Then, the signal is totally reflected by the receiver (or at a receiver-side end of the transmission line) and returns to the driver without being damped. If the output impedance Zout is equal to the impedance Z0, the reflected signal is terminated (or absorbed) at a driver-side end of the transmission line (or at a connection point between the transmission line and the driver).
However, the output impedance Zout actually depends on a voltage of the output signal because the driver is not ideal. Accordingly, part of the reflected signal is further reflected by the driver (or at the driver-side end of the transmission line) and travels for the receiver again. Thus, the output signal of the driver is repeatedly reflected by the receiver and the driver.
To suppress the above mentioned multiple reflection between the driver and the receiver, another related semiconductor apparatus has a terminating resistor connected to the receiver-side end of the transmission line.
However, the terminating resistance uselessly consumes electric power. That is, the semiconductor apparatus including the terminating resistor has high electricity consumption. Furthermore, the terminating resistance increases manufacturing steps of the semiconductor apparatus and thereby increases the production cost of the semiconductor apparatus.